/* libFLAC - Free Lossless Audio Codec library
 * Copyright (C) 2004,2005,2006,2007  Josh Coalson
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the Xiph.org Foundation nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#if HAVE_CONFIG_H
    #include <config.h>
#endif

#include "public/assert_flac.h"

#include "private/float.h"

#ifdef FLAC__INTEGER_ONLY_LIBRARY

/* adjust for compilers that can't understand using LLU suffix for uint64_t literals */
    #ifdef _MSC_VER
        #define FLAC__U64L(x) x
    #else
        #define FLAC__U64L(x) x##LLU
    #endif

const FLAC__fixedpoint FLAC__FP_ZERO = 0;
const FLAC__fixedpoint FLAC__FP_ONE_HALF = 0x00008000;
const FLAC__fixedpoint FLAC__FP_ONE = 0x00010000;
const FLAC__fixedpoint FLAC__FP_LN2 = 45426;
const FLAC__fixedpoint FLAC__FP_E = 178145;

/* Lookup tables for Knuth's logarithm algorithm */
    #define LOG2_LOOKUP_PRECISION 16
static const FLAC__uint32 log2_lookup[][LOG2_LOOKUP_PRECISION] = {
    {
        /*
         * 0 fraction bits
         */
        /* undefined */ 0x00000000,
        /* lg(2/1) = */ 0x00000001,
        /* lg(4/3) = */ 0x00000000,
        /* lg(8/7) = */ 0x00000000,
        /* lg(16/15) = */ 0x00000000,
        /* lg(32/31) = */ 0x00000000,
        /* lg(64/63) = */ 0x00000000,
        /* lg(128/127) = */ 0x00000000,
        /* lg(256/255) = */ 0x00000000,
        /* lg(512/511) = */ 0x00000000,
        /* lg(1024/1023) = */ 0x00000000,
        /* lg(2048/2047) = */ 0x00000000,
        /* lg(4096/4095) = */ 0x00000000,
        /* lg(8192/8191) = */ 0x00000000,
        /* lg(16384/16383) = */ 0x00000000,
        /* lg(32768/32767) = */ 0x00000000
    },
    {
        /*
         * 4 fraction bits
         */
        /* undefined */ 0x00000000,
        /* lg(2/1) = */ 0x00000010,
        /* lg(4/3) = */ 0x00000007,
        /* lg(8/7) = */ 0x00000003,
        /* lg(16/15) = */ 0x00000001,
        /* lg(32/31) = */ 0x00000001,
        /* lg(64/63) = */ 0x00000000,
        /* lg(128/127) = */ 0x00000000,
        /* lg(256/255) = */ 0x00000000,
        /* lg(512/511) = */ 0x00000000,
        /* lg(1024/1023) = */ 0x00000000,
        /* lg(2048/2047) = */ 0x00000000,
        /* lg(4096/4095) = */ 0x00000000,
        /* lg(8192/8191) = */ 0x00000000,
        /* lg(16384/16383) = */ 0x00000000,
        /* lg(32768/32767) = */ 0x00000000
    },
    {
        /*
         * 8 fraction bits
         */
        /* undefined */ 0x00000000,
        /* lg(2/1) = */ 0x00000100,
        /* lg(4/3) = */ 0x0000006a,
        /* lg(8/7) = */ 0x00000031,
        /* lg(16/15) = */ 0x00000018,
        /* lg(32/31) = */ 0x0000000c,
        /* lg(64/63) = */ 0x00000006,
        /* lg(128/127) = */ 0x00000003,
        /* lg(256/255) = */ 0x00000001,
        /* lg(512/511) = */ 0x00000001,
        /* lg(1024/1023) = */ 0x00000000,
        /* lg(2048/2047) = */ 0x00000000,
        /* lg(4096/4095) = */ 0x00000000,
        /* lg(8192/8191) = */ 0x00000000,
        /* lg(16384/16383) = */ 0x00000000,
        /* lg(32768/32767) = */ 0x00000000
    },
    {
        /*
         * 12 fraction bits
         */
        /* undefined */ 0x00000000,
        /* lg(2/1) = */ 0x00001000,
        /* lg(4/3) = */ 0x000006a4,
        /* lg(8/7) = */ 0x00000315,
        /* lg(16/15) = */ 0x0000017d,
        /* lg(32/31) = */ 0x000000bc,
        /* lg(64/63) = */ 0x0000005d,
        /* lg(128/127) = */ 0x0000002e,
        /* lg(256/255) = */ 0x00000017,
        /* lg(512/511) = */ 0x0000000c,
        /* lg(1024/1023) = */ 0x00000006,
        /* lg(2048/2047) = */ 0x00000003,
        /* lg(4096/4095) = */ 0x00000001,
        /* lg(8192/8191) = */ 0x00000001,
        /* lg(16384/16383) = */ 0x00000000,
        /* lg(32768/32767) = */ 0x00000000
    },
    {
        /*
         * 16 fraction bits
         */
        /* undefined */ 0x00000000,
        /* lg(2/1) = */ 0x00010000,
        /* lg(4/3) = */ 0x00006a40,
        /* lg(8/7) = */ 0x00003151,
        /* lg(16/15) = */ 0x000017d6,
        /* lg(32/31) = */ 0x00000bba,
        /* lg(64/63) = */ 0x000005d1,
        /* lg(128/127) = */ 0x000002e6,
        /* lg(256/255) = */ 0x00000172,
        /* lg(512/511) = */ 0x000000b9,
        /* lg(1024/1023) = */ 0x0000005c,
        /* lg(2048/2047) = */ 0x0000002e,
        /* lg(4096/4095) = */ 0x00000017,
        /* lg(8192/8191) = */ 0x0000000c,
        /* lg(16384/16383) = */ 0x00000006,
        /* lg(32768/32767) = */ 0x00000003
    },
    {
        /*
         * 20 fraction bits
         */
        /* undefined */ 0x00000000,
        /* lg(2/1) = */ 0x00100000,
        /* lg(4/3) = */ 0x0006a3fe,
        /* lg(8/7) = */ 0x00031513,
        /* lg(16/15) = */ 0x00017d60,
        /* lg(32/31) = */ 0x0000bb9d,
        /* lg(64/63) = */ 0x00005d10,
        /* lg(128/127) = */ 0x00002e59,
        /* lg(256/255) = */ 0x00001721,
        /* lg(512/511) = */ 0x00000b8e,
        /* lg(1024/1023) = */ 0x000005c6,
        /* lg(2048/2047) = */ 0x000002e3,
        /* lg(4096/4095) = */ 0x00000171,
        /* lg(8192/8191) = */ 0x000000b9,
        /* lg(16384/16383) = */ 0x0000005c,
        /* lg(32768/32767) = */ 0x0000002e
    },
    {
        /*
         * 24 fraction bits
         */
        /* undefined */ 0x00000000,
        /* lg(2/1) = */ 0x01000000,
        /* lg(4/3) = */ 0x006a3fe6,
        /* lg(8/7) = */ 0x00315130,
        /* lg(16/15) = */ 0x0017d605,
        /* lg(32/31) = */ 0x000bb9ca,
        /* lg(64/63) = */ 0x0005d0fc,
        /* lg(128/127) = */ 0x0002e58f,
        /* lg(256/255) = */ 0x0001720e,
        /* lg(512/511) = */ 0x0000b8d8,
        /* lg(1024/1023) = */ 0x00005c61,
        /* lg(2048/2047) = */ 0x00002e2d,
        /* lg(4096/4095) = */ 0x00001716,
        /* lg(8192/8191) = */ 0x00000b8b,
        /* lg(16384/16383) = */ 0x000005c5,
        /* lg(32768/32767) = */ 0x000002e3
    },
    {
        /*
         * 28 fraction bits
         */
        /* undefined */ 0x00000000,
        /* lg(2/1) = */ 0x10000000,
        /* lg(4/3) = */ 0x06a3fe5c,
        /* lg(8/7) = */ 0x03151301,
        /* lg(16/15) = */ 0x017d6049,
        /* lg(32/31) = */ 0x00bb9ca6,
        /* lg(64/63) = */ 0x005d0fba,
        /* lg(128/127) = */ 0x002e58f7,
        /* lg(256/255) = */ 0x001720da,
        /* lg(512/511) = */ 0x000b8d87,
        /* lg(1024/1023) = */ 0x0005c60b,
        /* lg(2048/2047) = */ 0x0002e2d7,
        /* lg(4096/4095) = */ 0x00017160,
        /* lg(8192/8191) = */ 0x0000b8ad,
        /* lg(16384/16383) = */ 0x00005c56,
        /* lg(32768/32767) = */ 0x00002e2b
    }
};

    #if 0
static const FLAC__uint64 log2_lookup_wide[] = {
    {
        /*
         * 32 fraction bits
         */
        /* undefined */ 0x00000000,
        /* lg(2/1) = */ FLAC__U64L(0x100000000),
        /* lg(4/3) = */ FLAC__U64L(0x6a3fe5c6),
        /* lg(8/7) = */ FLAC__U64L(0x31513015),
        /* lg(16/15) = */ FLAC__U64L(0x17d60497),
        /* lg(32/31) = */ FLAC__U64L(0x0bb9ca65),
        /* lg(64/63) = */ FLAC__U64L(0x05d0fba2),
        /* lg(128/127) = */ FLAC__U64L(0x02e58f74),
        /* lg(256/255) = */ FLAC__U64L(0x01720d9c),
        /* lg(512/511) = */ FLAC__U64L(0x00b8d875),
        /* lg(1024/1023) = */ FLAC__U64L(0x005c60aa),
        /* lg(2048/2047) = */ FLAC__U64L(0x002e2d72),
        /* lg(4096/4095) = */ FLAC__U64L(0x00171600),
        /* lg(8192/8191) = */ FLAC__U64L(0x000b8ad2),
        /* lg(16384/16383) = */ FLAC__U64L(0x0005c55d),
        /* lg(32768/32767) = */ FLAC__U64L(0x0002e2ac)
    },
    {
        /*
         * 48 fraction bits
         */
        /* undefined */ 0x00000000,
        /* lg(2/1) = */ FLAC__U64L(0x1000000000000),
        /* lg(4/3) = */ FLAC__U64L(0x6a3fe5c60429),
        /* lg(8/7) = */ FLAC__U64L(0x315130157f7a),
        /* lg(16/15) = */ FLAC__U64L(0x17d60496cfbb),
        /* lg(32/31) = */ FLAC__U64L(0xbb9ca64ecac),
        /* lg(64/63) = */ FLAC__U64L(0x5d0fba187cd),
        /* lg(128/127) = */ FLAC__U64L(0x2e58f7441ee),
        /* lg(256/255) = */ FLAC__U64L(0x1720d9c06a8),
        /* lg(512/511) = */ FLAC__U64L(0xb8d8752173),
        /* lg(1024/1023) = */ FLAC__U64L(0x5c60aa252e),
        /* lg(2048/2047) = */ FLAC__U64L(0x2e2d71b0d8),
        /* lg(4096/4095) = */ FLAC__U64L(0x1716001719),
        /* lg(8192/8191) = */ FLAC__U64L(0xb8ad1de1b),
        /* lg(16384/16383) = */ FLAC__U64L(0x5c55d640d),
        /* lg(32768/32767) = */ FLAC__U64L(0x2e2abcf52)
    }
};
    #endif

FLAC__uint32 FLAC__fixedpoint_log2(FLAC__uint32 x, unsigned fracbits, unsigned precision)
{
    const FLAC__uint32 ONE = (1u << fracbits);
    const FLAC__uint32* table = log2_lookup[fracbits >> 2];

    FLAC__ASSERT(fracbits < 32);
    FLAC__ASSERT((fracbits & 0x3) == 0);

    if (x < ONE)
        return 0;

    if (precision > LOG2_LOOKUP_PRECISION)
        precision = LOG2_LOOKUP_PRECISION;

    /* Knuth's algorithm for computing logarithms, optimized for base-2 with lookup tables */
    {
        FLAC__uint32 y = 0;
        FLAC__uint32 z = x >> 1, k = 1;
        while (x > ONE && k < precision)
        {
            if (x - z >= ONE)
            {
                x -= z;
                z = x >> k;
                y += table[k];
            }
            else
            {
                z >>= 1;
                k++;
            }
        }
        return y;
    }
}

#endif /* defined FLAC__INTEGER_ONLY_LIBRARY */